John ericsson



` TED STATES PATENT OFFICE.

JOHN ERICSSON, OF NEW YORK, N. Y.

SCREW-PROPELLER.

Specification of Letters Patent No. 4,181, dated September 9, 1845.

To all whom t may concern:

Be it known that I, J oHN ERICSSON, of the city, county, and State ofNew York, have invented an Improved Propeller for Steam Navigation, andI do hereby declare that the following is a full, clear, and exactdescription of the construction and operation ot the same, referencebeing had to the annexed drawings, making a part of this speciicationand herein below more particularly referred to.

My inventio-n consists: 1. In a cylindrical hub or center block tosustain the spiral propelling blades constructed with a series ofprojections, one side of which radiates while the other is curved, eachof which projections is perforated with a hole corresponding to itsexterior form, and at the base of each ot' which a notch is cut in thehub to receive t-he tapered extremity of the propelling blades, whichare riveted severally to the radial side of the said projections. 2. Ina series of elliptic braces, placed diagonally to the vertical plane ofthe propeller, corre spending to the number of propelling blades, andattached Zig-zag to alternate and opposite sides of the same. They aremade narrow, being less than half the width of the propelling blades atthe point where they are attached, but by alternating they give acontinuous support to the same for nearly the whole extent of theirwidth, while the diagonal disposition of the braces prevents the illeffects that ,would otherwise result from the twisting action to whichthe spiral blades are subjected.

Description of drawings hereto annexed illustrating my invention-Figurel, is a side elevation of the propeller, representing a fore-shortenedview of its blades with the elliptic braces. Fig. 2 cut section throughthe central vertical plane of the propeller, as marked by a red line yin Fig. l.4 Fig. 8, front view of the hub with its perforatedprojections-upon an enlarged scale. Fig. 4 top view of one of theelliptic braces and Fig. 5 a longitudinal section of said brace througha line drawn at right angles to its ends, as indicated by the red line.e a in Fig. 4; both upon an enlarged scale. Fig. 6, top view of one ofthe propelling blades.

Similar parts in all the igures are indicated by the same letters ofreference.

A the hub. a, hole through center of hub through which the propellershaft passes,

c. c c c 0 vc projections on the hub. c radial side of projection whichextends across the whole width ofthe hub at an angle to its center line,and is made winding to coincide with the thread of a screw. c curvedside of the projection connecting the outer end of the said radial sideto the circumference of the hub. c a notch formed at the base of saidradial sidefor receiving the end of the propelling blade. 0', open spacethrough which the water passes freely during the progress of the vesseland the rotation of the propeller. D propelling blades made to enter thenotch c and riveted to the radial side of the projection c at d. d',bead or flange formed at the extreme circumference of the propellingblades to give strength and stiffness to the same. E elliptic braces,attached to the propelling blades by means of rivets at c at which placea bead or projection, is formed on the back ci the blade to make goodthe strength lost by the requisite perforations for said rivets; theblade having also a similar projection for the same.

Having now described the various parts of the improved propeller, I willproceed to speak ot' their use, fitness and peculiar character. Themotion of the propeller in driving the vessel ahead being indicated bythe arrows marked on the plan, it will be seen that the pressure of thewater against the propelling blades will force them against the radialsides of the projections on the hub without causing any strain on therivets at d, since the narrow end of the blade is inserted in the notchat c, where it is thus held firmly, while the extreme point of theprojection c acts as a fulcrum or point of sup port; it will also beseen that the strain to which the blades or arms of all spiralpropellers are necessarily subjected at the point where they Vleave thehub, is here entirely prevented by the introduction of the curved sideof the projection without the use of any thick substance to causeresistance in passing through the water. With reference to the ellipticbraces, it is to be particularlyV noticed that although they are madenarrow, yet by being placed Zig-zag a continuous support is given to thepropelling blades for nearly the whole extent of their width; and it isalso to be particularly noticed, that the twisting action to which theoblique plates are subjected is most thoroughly prevented by thediagonal position of the said elliptic braces. The bead introduced at eand d add as much strength to the propelling blades as is taken away bythe holes made for the rivets, While the bead cl gives great strengthand stability Without adding anything scarcely to the Weight. It is alsoimportant to notice, that by cutting out the rivets at c and Z any oneblade may be removed and replaced Without deranging the structure.

New l do not claim as my invention the application to purposes ofpropulsion of spiral blades radiating from and fastened to a centerblock or hub, Letters Patent for the J. ERICSSON.

Witnesses:

JOHN O. SARGENT,

GEO. W. MORTON.

